There was a dyno day today at a local performance diesel shop today and I had a chance to run the rollers.<br>Stone stock, my truck put 179hp and 516 ft lbs of torque to the rear wheels. We plugged in my EZ box and it went to 206 and 700 respectively.<br>Now I just have to wait a week and a half to get the 4&quot; exhaust and cold air intake installed and see where the numbers go from there!!!<br>Just thought I'd let you guys know! ;D

The EZ didn't give you very much HP did it? Mine dynoed 178 stock and 236hp with the EZ. I have heard that injectors work better on the HO's than the boxes, must be something to it.

We noticed the HP was down, but we also didn't install the boost elbow yet and I am running a larger tire ( 305/70 instead of stock 265/75) Dyno is also at 4000 ft of elevation which will make a difference.<br> I'll post the numbers, stock and all toys installed after the 16th when it will be dyno'd at sea level and then it get's dyno'd again at 4000 ft so we can compare numbers. The local shop is interested in the difference.

Don't know if you will notice a whole lot of difference, I'm over 4k ft here too. Lets us know tho. :)

I don't want to throw stones here, but &quot; Their &quot; dyno is always showing huge torque and low HP.. I would be careful on their numbers... <br><br>For comparison, at our dyno day we saw consistent numbers from stock PSD's at 209 and Stock ETC's at just over 200 at the rear wheels.<br><br>Heck even my 93 does over 200.. THe G-tech also agrees with this dyno...<br><br>Be careful Homestead....<br><br>J-eh

My stock ETH 6 spd dyno'd at the same elevation in the same town on a dynojet was 221 at the rear wheels bone stock but no way did I have that torque. I also had 221 HP stock in Vegas. I never could figure out how the torque and HP numbers had so much of a spread where you did your test. Real world will tell ya.
Also, do not expect any power increase with an exhaust or an intake. The only time you might see some HP [less then 10] from an exhaust upgrade, you would have to be at the limits of the 3&quot; exhaust...and that would have to be at the 325-375 HP range. Food for thought.

Your numbers at sea level [I am guessing in BC...abbottsford?] will be higher by a small amount because of elevation. The air is more dense out west.

Your RWHP would be in the 220-245 range on a stock ETH. With torque in the range of 460 lb ft. Some ETH trucks have some high factory HP numbers.

Add the EZ and it should be around 30 RWHP higher and torque in the range of 510...give or take a bit.
Good luck with your testing. ;D

What gear was used during that dyno run? How was the torque calculated? High torque and low hp sounds like a lower gear was used, or a wrong reading on the rpms, wrong math calculation, or something along those lines.

I wondered about the low HP number ??? I know there is driveline loses, but 60 some HP thru a manual trans. I am running a 3:54 gear with tires about an inch and a half taller than stock, so that would make a difference but not that much. <br> I know every dyno is different as well as a dyno operator is looking for a smooth curve not a spike. They did 3 pulls on the truck when in stock trim and the 2nd pull gave the numbers I presented. With the EZ, it was pulled twice. The first run was aborted because the truck wouldn't load the rollers, it just hazed the tires. There was a different truck dyno'd between my sets of pulls.<br>There were 3 other 02 HO Rams run that day, all with stock 265/75 rubber, and they all ran similar numbers with and without the EZ. Their HP and Torque were slightly higher, given the tire size. At least it gives my numbers some consistency, not a &quot;fluke&quot; reading.<br>I'm not taking the numbers and &quot;living by them&quot;. As long as I'm happy with the seat of the pants test, what more can I ask for! It looks good, goes good, good enough ;D<br>All these mods are honestly being done to, yes, give me a little more poop, but more for reliability and mileage. More air in and out means cooler running temps, exhaust brake saves me some service brake wear, EZ gives a little more snort.<br>I'm happy!!!<br><br>I'll keep you posted on the changes, thanks again for your input, it's much appreciated!

the ez will give you about 35 peak hp. but at 2000rpm it willl give you over 60. <br><br>jim

What effect do larger tires have on the numbers? Will they be higher or lower?

Larger tires will cause the #s to be lower depending on how much bigger around they are, its like putting higher gears in it.

...uh...guess that was a dumb question huh ::) I hate it when that happens...

Was this a dynojet dyno?

That WILL account for inflated or skewed numbers. I've been to a few dynos now, the ones that seem best are Superflow and Mustangs.

Read up on Dynojets - not good for tuning. They spin a &quot;known mass,&quot; not a mass that's equivalent to running your truck down the road.

We found this out the hard way - tuned a Lightning pickup on dynojet by CHT/EGTs, and found that the real world added about 300 degrees F higher temps - and could have burnt holes in pistons had we let it run lean much longer. Oh well - that's a topic for another forum...

<br> Larger tires will cause the #s to be lower depending on how much bigger around they are, its like putting higher gears in it.<br><br><br>maybe -- depends on the machine used and how the dyno test itself is conducted. In theory, you are right that a larger tire will contribute torque multiplication and cause lower torque to the road. I suspect, however, that real world dyno tests correct for that.<br><br>The transmission gear, the rear end, and the tire diamter all contribute to torque multiplication and actual torque delivered to the pavement. I could be wrong about this, but I believe that the dyno simply compares the engine rpm to that to its own roller rpm and bingo--you have instant normalization of drifveline configurations. So the dyno doesn't care about your gears and tires -- you just have to tell it what the engine rpm is and it figures out the rest. So if that is the case then no--larger tire sizes will not impose a different final drive gear ratio and cause a lower torque reading. There may be other tire-loss related factors contributing, but tire height is not one of them. That is, unless I'm wrong about the way dyno test are actually performed.<br><br>

Well any dyno can just measure or calculate the force applied and the speed of its drum. The force is either produced by a brake or by inertia of the rollers. A certain force@ a certain speed is power. That is on the wheels. If you measure engine RPM you can calculate torque. And print some blue and red curves. I used several Bosch dynos (calibrated for proof of evidence in court) which used brakes (electromagnetic) I found that if you let spinup happen too fast on these dynos you'll get weird numbers for turbocharded engines. (EG boost comes up slower than vehicle accelerates). Bigger or smaller tires should not make change your numbers. Actually on an inertia dyno bigger tires should increase the numbers because you have more time to get up to boost. <br>Maybe somebody can make sense of this garbled english...<br><br>AlpineRAM

<br>Well any dyno can just measure or calculate the force applied and the speed of its drum. <br><br>Indeed. To be precise, the dyno measures force (thats what torque is) directly. But, left at that, the measured torque is rather meaningless and depends heavily upon the driveline ratio used at the time (transmission gear, rear end gear, tire size) so the question is one of how to interpret the results -- what meaning does the measured torque number have? So we are most interested in a number that corresponds directly to flywheel torque minus driveline losses. <br><br>at the core, the dyno is kind of dumb -- all it measures is the force required to keep the drum from accelerating. Thats measured torque to the road. everything else is calculated.<br><br><br><br>The force is either produced by a brake or by inertia of the rollers. <br><br>For those who care, this means that the force applied by the dyno in resistance to the truck's tires is equal and opposite to what the tires deliver. So thats how the force (torque) is measured directly.<br><br><br>A certain force@ a certain speed is power. That is on the wheels. <br><br><br>yep. I'm not accustomed to seeing power defined that way, but technically you're right. Power is defined as force times distance divided by time. So therefore, power is force times speed.<br><br><br>If you measure engine RPM you can calculate torque. And print some blue and red curves. <br><br><br>well, the dyno measures torque directly without knowing engine RPM, but your right in that it calculates a meaningful torque number using engine RPM. All it does is compare the rpm of the rollers with the rpm of the engine and, voila, you have flywheel torque, calculated from measured torque. And if you accurately measure engine rpm, then the numbers are more accurate.<br><br>I used several Bosch dynos (calibrated for proof of evidence in court) which used brakes (electromagnetic) I found that if you let spinup happen too fast on these dynos you'll get weird numbers for turbocharded engines. (EG boost comes up slower than vehicle accelerates). Bigger or smaller tires should not make change your numbers. Actually on an inertia dyno bigger tires should increase the numbers because you have more time to get up to boost. <br>Maybe somebody can make sense of this garbled english...<br><br>AlpineRAM<br><br><br>the last part went right past me. Unless there is slippage or losses in the tire/roller interface, or in an slush box (automatic transmission) then the dyno won't care how fast anything spools up. my guess is that slippage is the cause of the weird numbers -- if you spin up too fast, the tires will break loose and you'll get lower torque numbers.

sorry I messed up on the quoting :P

The last opart looks like this- you won't see max power in first gear while driving because the truck will rev into the governor before having much boost. In OD or 5th or 6th gear you will have full power because the gear ratio is high enough to let you make boost before hitting the governor. If you use a dyno which regulates the brake so that you can accelerate from 30 to 60 mph within 3 seconds you'll see lower numbers than on the same dyno set to 10 seconds 30to60 mph time. On an inertia dyno you just have inertia as a brake. So if you'd measure in first gear the same thing as on the road would happen- you hit the governor almost instantly and therefore you don't accelerate anymore. Then you try the same thing in 5th gear and accelerating the same mass from 1-5 mph takes less time than from 10 to 50 (I know our gears are different) so you have more time to spin up the turbo, you get more boost, so more fueling is possible ( Either the AFC or ist software brother in the ECU don't want you to smoke). So using bigger tires gives you a longer overall ratio, and on an inertia dyno where the rollers are just right to simulate a Mustang or corvette, you will see lower power for a turbodiesel with a short ratio.<br>Easy way to determine this for yourself- drive up a mountain in the highest gear where you can sustain 1600 rpm - watch your boost. Then see whether you have the same boost @1600 rpm while on the dyno. <br>AlpineRAM

<br>The last opart looks like this- you won't see max power in first gear while driving because the truck will rev into the governor before having much boost. <br><br>under normal driving conditions, certainly. under sufficient load, you'll see max power. I just don't know of many situations what will provide sufficient load in first gear! Thats because torque to the wheels is very very high -- near 10,000 ft lbs for a 6-speed! <br><br>In OD or 5th or 6th gear you will have full power because the gear ratio is high enough to let you make boost before hitting the governor. <br><br>well, thats just because you've found a way to load the engine sufficiently. Its not about gears necessarily, its about load, although certainly the lower gears are harder to load due to the tremendous force (torque) applied to the wheels.<br><br>If you use a dyno which regulates the brake so that you can accelerate from 30 to 60 mph within 3 seconds you'll see lower numbers than on the same dyno set to 10 seconds 30to60 mph time. <br><br>ahh its becoming clear now. the dyno regulates the brake to accomodate certain acceleration goals. But without regard to that, the only reason you see lower numbers is becuase the dyno is not &quot;pushing back&quot; on the truck as much as the truck is pushing -- otherwise you wouldn't accelerate!<br><br>On an inertia dyno you just have inertia as a brake. So if you'd measure in first gear the same thing as on the road would happen- you hit the governor almost instantly and therefore you don't accelerate anymore. Then you try the same thing in 5th gear and accelerating the same mass from 1-5 mph takes less time than from 10 to 50 (I know our gears are different) so you have more time to spin up the turbo, you get more boost, so more fueling is possible ( Either the AFC or ist software brother in the ECU don't want you to smoke). So using bigger tires gives you a longer overall ratio, and on an inertia dyno where the rollers are just right to simulate a Mustang or corvette, you will see lower power for a turbodiesel with a short ratio.<br><br>I see. so my question here is this: why not use a brake and load the truck to its own sweet spot for pulling? If the dyno could arbitrarily apply a constant load at some speed, then you could bring the truck up to wot fully loaded and topped out at its maximum rpm (sort of a stall speed for the truck). Are there any dynos that will do that? That would be one monster heat dissipation problem for the dyno! <br>

The Superflow dyno we used at the Diesel Dyno Stampede is a load dyno.. The brakes are applied in order to create a peak power number. Its used for highway tractors mainly and can bring a Signature 600 to a full stop in any gear LOL...<br><br>The way it works is not like the others. You go to full RPM (depending on your governor tweeks) and hold it there. Then the load is applied until the RPM begins to drop at a certain percentage to a low setpoint of say 2000 RPM. This gives you a curve and the HP numbers. With engine RPM the Torque is calculated.<br><br>The Superflow is the only way to go for guys like me with no wastegate and don't drag race. I have the time and ability to fully load the engine and bring it to its knees..LOL... The numbers are consistent and repeatable.<br><br>The guys &quot;up the road&quot; with their dyno from us never get the right #'s IMHO.<br><br>J-eh

Well the small inertia dynos are good for simulating acceleration of a car. That's what counts for most users. A drag racer can't use 50000000HP if they are available 30minutes after the start. Since the inertia dynos have an inertia to simulate lets say a corvette or some less they will easyly read wrong for trucks. I don't know the superflow, but the Bosch dyno uses either a magnetic brake or a hydraulic brake to load the engine. Usually we ran the tests upwards. So you start at some RPM, typical 1500 for passenger cars, go to WOT and let the dyno apply the brake till it holds the RPM. Then you let RPM climb very slowly- something like 10secs per 100 RPM or even slower depending on the vehicle. <br>Heat dissipation is a problem that occurs for the dyno- our LPS dyno had a water cooling with 3 cubic meters of reservoir and some massive coolers. <br>Sorry for any spelling errors, its past midnight over here..<br><br>AlpineRAM

guys, thanks for the primers on dynos. I was approaching the issue from the standpoint of pulling. not knowing how actual dynos are made, I assumed that the natural thing to do would be to apply a break and dissipate the heat. I can see that inertia dynos are cool for accleration, but really if you want to do that, you can get one of those $150 devices with an electronic accelerometer and accomplish the same thing!<br><br>well, almost. electronic, semiconductor accelerometers are very accurate, and the physics/mathematical proofs of accuracy are solid and robust. The idea is that the accelerometer itsef measures accleration directly and provides an electrical signal that can be processed. well, voila! a little mathematical hand waving (electronic processing) and you have a hand-held inertial dynomometer. Only problem is that electronic accelerometers are only good to about 0-60 in 7 seconds. they're not capable of measuring faster accelerations, so these devices are not so great for funny cars, but great for trucks :-)<br><br>But a good, stout break dyno is arguably the best bet for truck pulls :-).

Manual tranny guys should be using 4th gear (direct drive - not overdrive, and not underdrive) for minimal frictional losses through the trans. 4th gear is that gear in the NV4500s. I am not sure about 5600s - can someone confirm?<br><br>At least that's how they have us do it in Omaha... seemed to make sense to me.<br><br>-scott

<br> Dyno is also at 4000 ft of elevation which will make a difference.<br> <br><br>Do you have data to back this up?I mean, how do you know? I hear this argument all the time that altitude affects diesels dramatically. Altitude is not as big a factor as one may think for us.

I didn't think altitude would be as big a factor on a Turbo Diesel as on a naturally aspirrated gasser.<br><br>Sure, there's less air for the turbo to compress, but compressed is still compressed.<br>Might take it a bit longer to get the boost up, but once it's up there it is.<br><br><br>phox<br><br>

<br>Manual tranny guys should be using 4th gear (direct drive - not overdrive, and not underdrive) for minimal frictional losses through the trans. 4th gear is that gear in the NV4500s. I am not sure about 5600s - can someone confirm?<br><br>At least that's how they have us do it in Omaha... seemed to make sense to me.<br><br>-scott<br><br><br>for the 6-speed, this is 5th. But why does that minimize frictional losses through the tranny? in other words, why does the number of teeth on a gear matter? -- or is the gearing itself simpler (fewer frictional parts)? Makes sense if using the 1:1 gear ratio actually eliminates a gear in the drivetrain, though. other than that, it shouldn't make any difference.

Doug- direct gear usually is just a dog clutch between input and output shaft. So there are no gears involved.Nor is the countershaft turning. This reduces friction losses.
We usually measured for friction losses in the racecars. You win or loose with the power on the wheels. For the daily driver friction losses can be very interesting.All those beautiful horsepowers used for heating tranny oil or grinding away some expensive parts...

AlpineRAM

Lawrence from DD used to work for Dynojet before starting in business for himself. He's logged thousands of hours of dyno time and is probably THE formost expert on Dynojets, and possibly dynos in general, in the country. Once he even spent over 2 weeks dyno testing different rear end gear lash settings for optimal power, for a NASCAR team. DD uses overdrive on its dyno runs to help with turbo spoolup. <br><br>This method doesn't necessarily work on other dynos, such as a Mustang for example, because of the high roller speeds involved. Direct drive works better on those dynos.

at my work we have a rule of thumb thatyou lose 1% power for every 1000' of elevation for turbo charged engines and 3% for naturally aspirated. ever heard of this?

Anyone who thinks that altitude does not affect a diesel needs to take a Detroit 238 (6-71) grossing 80,000 up a pass over 7,000 feet. What is neat is the old locomotive effect with the smoke trail that you can see for the last 10 miles or so back down the road. And then there was the B-61, naa I won't even go there. Modern engines have enough power to mask the loss to a great extent. I put over 1,000,000 miles on the old 238 years ago. Of course that was when a 318 was a big motor ;D

Now I'm confused!!<br><br>As you guys may have been keeping track, I was heading down to BD-Power have my truck tweaked. They installed my guages, EZ box, 4&quot; turbo back exhaust, exhaust brake, and cold air intake. I had it dyno'd at home (4000 ft elevation) and it came out 179 hp/ 516 torque stone stock. With the EZ plugged in for kicks, it went 206/700. <br>Now on BD-Powers dyno, the same type as at home base, it went 265/748. Are these numbers at least close to realistic?<br>I know there are variations in dyno pulls and such. Personally, I don't care, because the truck just plain runs awesome!!! I am more than happy with the performance, my mileage has gone up, and it runs cooler. Are these numbers close to what they should be considering my mods?<br>On a side note, If you have the opportunity to deal with BD-Power, you will be impressed. They rolled my truck into the install bay at 8:00 am and it was done at 3:00 pm. Other than seeing the toys installed, you would never have known that they touched the truck. It was clean, no fingerprints, marks in the paint, pieces of wiring in the cab, nothing!! Everything was explained to me about how it works, do and don'ts, parameters to stay within.<br>It's a totally different truck, ME HAPPY!!!<br><br>Thanks guys for your input!

<br>Doug- direct gear usually is just a dog clutch between input and output shaft. So there are no gears involved.Nor is the countershaft turning. This reduces friction losses. <br>We usually measured for friction losses in the racecars. You win or loose with the power on the wheels. For the daily driver friction losses can be very interesting.All those beautiful horsepowers used for heating tranny oil or grinding away some expensive parts... <br><br>AlpineRAM <br><br><br>Alpine, the countershaft always turns, is driven from the input shaft.

Hauling: The countershaft turns- correct. But you transfer powe over the dog clutch of the direct drive. So there is not muck loss in it because you transfer the power without meshing gears. The little bit of power to overcome bearing drag of the countershaft is not where the power really goes.<br><br>AlpineRAM

Homestead , Think of a dyno run as a photograph. Its merely a snapshot in time reflecting the HP &amp; Tq the egine produced on THAT day at THAT time, elevation , barometric pressure , humidity , temperature etc etc . Its nearly impossible to produce consistent figures Without rigidly controlled enviromental conditions. I would suggest looking at your initial readings as a baseline and focus on relative gains produced on a dyno at consistent elevation / barometric pressure. Don't become infatuated by dyno readings [eyecrazy] cause they're all different. In the performance car world , I see countless posers attempting to race their dyno sheets ???! Do not allow yourself to fall into the dyno trap !! They are great tuning tools but have minimal relevance to ...say...how a race car will perform at the track.

<br>Hauling: The countershaft turns- correct. But you transfer powe over the dog clutch of the direct drive. So there is not muck loss in it because you transfer the power without meshing gears. The little bit of power to overcome bearing drag of the countershaft is not where the power really goes.<br><br>AlpineRAM<br><br><br>Alpine I was not inferring that the countershaft consumed power, just that it always turns if the clutch is engaged. Makes a good oil pump though, and is responsible for lubeing the rest of the transmission.

Hauling: Didn't want to critizise you. <br>You are correct that the countershaft always turns and transports the oil to the gear flanges. I did reply to a question why to use direct gear on the dyno. <br><br>AlpineRAM